[cnn-photo-caption image=http://i2.cdn.turner.com/cnn/2008/POLITICS/12/28/obama.gaza/art.obamaeconomy.gi.jpg caption="Barack Obama's approach to the Middle East as president will be the subject of much scrutiny."]
(CNN) - The president-elect's senior adviser said that while Barack Obama is monitoring the situation in Gaza closely, "the fact is that there is only one president at a time."
"There's only one president who can speak for America at a time. And that president now is George Bush," senior adviser David Axelrod said in an interview that aired Sunday on CBS' "Face the Nation."
Israeli airstrikes continued pounding targets in Hamas-ruled Gaza on Sunday, in what Israel said was a response to escalating rocket attacks against southern Israel.
The fighting ignited eight days after a six-month Egypt-brokered cease-fire between Hamas and Israel expired.
Palestinian security sources said Sunday that at least 277 people had been killed and hundreds wounded.
Obama spoke with Secretary of State Condoleezza Rice on Saturday about the violence in Gaza, two transition aides told CNN.
Asked whether Obama takes on a passive role when talking to Rice, Axelrod said, "I would hardly describe him as passive."
"I think they have a good working relationship. And there's a - I think the calls are largely in the area of fact-finding for him," he said.
"But I think he wants to get a handle on the situation, so that, when he becomes president on January 20, he has the advantage of all the facts and information leading up to that point."